Object for storing SURF interest points






points = SURFPoints(location) constructs a SURFPoints object from an M-by-2 array of [x y] point coordinates.

points = SURFPoints(location,Name,Value) sets properties using one or more name-value pairs. Enclose each property name in quotes. For example, points = SURFPoints('Metric',0.0)

Input Arguments

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Point coordinates, specified as an M-by-2 array of form [x y] coordinates. M denotes the number of points.


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Number of points held by the object, specified as a numeric value.

Point locations, specified as an M-by-2 array of [x y] point coordinates.

Scale at which the feature is detected, specified as a value greater than or equal to 1.6.

Strength of detected feature, specified as a numeric value.


Sign of the Laplacian determined during the detection process, specified as -1, 0, or 1. You can use this parameter to accelerate the feature matching process.



Object Functions

plotPlot points
isemptyDetermine if points object is empty
lengthNumber of stored points
selectStrongestSelect points with strongest metrics
sizeReturn the size of a points object
selectUniformSelect uniformly distributed subset of feature points


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Read in image.

    I = imread('cameraman.tif');

Detect SURF features.

    points = detectSURFFeatures(I);

Display location and scale for the 10 strongest points.

    strongest = points.selectStrongest(10);
    imshow(I); hold on;


ans = 10x2 single matrix

  139.7482   95.9542
  107.4502  232.0347
  116.6112  138.2446
  105.5152  172.1816
  113.6975   48.7220
  104.4210   75.7348
  111.3914  154.4597
  106.2879  175.2709
  131.1298   98.3900
  124.2933   64.4942

Read in image.

    I = imread('cameraman.tif');

Detect SURF feature.

    points = detectSURFFeatures(I);

Display the last 5 points.

    imshow(I); hold on;


Although SURFPoints may hold many points, it is a scalar object. Therefore, numel(surfPoints) always returns 1. This value may differ from length(surfPoints), which returns the true number of points held by the object.


[1] Bay, H., A. Ess, T. Tuytelaars, and L. Van Gool. “SURF:Speeded Up Robust Features.” Computer Vision and Image Understanding (CVIU).Vol. 110, No. 3, pp. 346–359, 2008.

Extended Capabilities

Introduced in R2011b